The invention is in the field of multiple photoflash lamp units, such as planar arrays.
The above-referenced patent applications disclose multiple flash lamp units that can be connected to a camera in different orientations in each of which a different group of the flash lamps is relatively farther from the camera lens axis then are the other lamps of the unit. The lamps and electrical circuitry are arranged so that in any of the orientations of the unit with respect to the camera, only the group of lamps relatively farther from the lens axis can be flashed. The purpose of such an arrangement is to position the "active" group of flash lamps farther above the camera lens in order to reduce the possibility of a "red-eye" effect that causes the pupils of a person's eyes to appear red or pink in flash pictures taken when the flash lamp is close to the camera lens.
Each of the above-referenced multiple flash lamp arrays has, in a preferred embodiment, a circuit board having one or more integral plug-in connector tabs each provided with a plurality of electircal connection terminals in the form of conductive stripes printed on or otherwise attached to the connector tab. The various connector terminals are connected to individual lamps or to sequential firing circuitry carried on the circuit board and interconnected with lamps in the unit. Such flash units, and particularly if they employ high voltage types of flash lamps which are flashed by a high voltage pulse (1000 or 2000 volts, for example) of low energy, are prone to electrostatic firing of one or more lamps if a connection terminal is touched by or brought into close proximity to a person or object having an electrostatic charge. Such undesirable accidental flashing of lamps can also occur if the flash unit housing, which usually is made of a plastic material, acquires an electrostatic charge and a connector terminal is touched by or brought into close proximity to a person or object. The problem can also occur, and can be more severe, if both the plastic housing and the person or object near to or touching a connection terminal are electrostatically charged with relatively opposite polarities.
The first two of the above-referenced Cote patent applications disclose terminal circuit arrangements for reducing the likelihood of accidental flashing of lamps by electrostatic charge when the terminals are touched while handling the unit. This is accomplished by making one of the terminals longer or otherwise more readily touchable than the others, and by connecting this more touchable terminal electrically in the unit so as to have more stray capacitance to ground than the other terminals.
The above-referenced patent application of Blount, Cote, and Zukowski discloses a circuit shield in the form of a metal film or foil carried on the back side of the circuit board and electrically connected to the more readily touchable terminal of the circuit.